The theft of two police-issue Glocks from New Plymouth Courthouse lockup must have been an inside job, Court Minister Chester Borrows says.

His concerns are echoed by Labour Party justice spokesman Andrew Little, who is calling for a high-level investigation into the thefts, describing such exhibits as "absolutely sacrosanct" to the legal process.

The Ministry of Justice has said it has no idea when the pistols, involved in the controversial Steven Wallace shooting at Waitara 14 years ago, were stolen.

Borrows said it was not a political matter but an operational one for police and the courts.

"The Ministry of Justice has been looking very closely at their processes around security because it's obvious no one walked in off the street [and took the Glocks]," Borrows said yesterday.

Police have declined this week to answer further questions as to who the prime suspects are in the ongoing theft investigation.

"No-one has been charged for the theft of the firearms, and we are not prepared to discuss any further details of our ongoing investigation, as this could jeopardise our inquiries," a police spokeswoman said.

A ministry spokesman yesterday echoed the police stance, saying the ministry did not want to add any further to the response given to the paper last week, and did not wish to jeopardise the police investigation.

Police have said the theft from the courthouse was discovered when police arrested Max Aramoana, 52, during a drugs operation in June last year.

One of the two Glocks police allegedly found at his home in Matiere in the Ruapehu District was traced back to the police shooting of Steven Wallace on April 30, 2000.

The Glocks had been kept in the evidential lockup in the New Plymouth Courthouse.

Aramoana was charged with the illegal possession of the Glocks. He next appears in the Hamilton District Court on June 6 on a raft of drugs and firearms charges.

Since the theft of the Glocks, court security for exhibits has been increased across the country, the ministry says.

"We know where they are located and who has access to them," a spokesperson said last week.

Yesterday, the minister said he had been informed the guns were still in the courts' care because the case had not been closed.

"I understand the reason why they remained in the care of court staff was because the Wallace family had indicated taking further action."

The usual process, following completion of an investigation and subsequent judicial hearings, was to return the firearms, worth about $2500 each, to service, he said.

"Maybe we need to look at a policy as to how long we keep valuable exhibits in the expectation of court cases way into the future.

"How long do you retain exhibits for procedures that may never eventuate?" Borrows asked.

Yesterday, Labour Party justice spokesperson Andrew Little said he would be taking the matter further and had very serious concerns about the loss of the pistols.

He found it "absolutely unbelievable" it could have been allowed to happen.

If there was no break-in, it pointed to an inside job, he said.

If the two Glocks could be stolen, what other evidential exhibits - which should be "absolutely sacrosanct" - and cases they were linked with had been put at risk, he asked. He was now considering asking questions in Parliament.

Police Minister Anne Tolley said the criminal investigation was ongoing.

"I can't interfere in that - and I would expect it to cover every aspect of this case," Tolley said.